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Lyme Disease
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Last updated January 1, 2014

Interpreting the IgG & IgM Western Blot For Lyme Disease

©2004 Melissa Kaplan


The IgG and IgM Western Blot provides results in a way that lets us visualize the patient's antibodies. It is more sensitive and specific than the ELISA and EIA (that is, it is more likely to show positives where the ELISA/EIA showed negatives). The IgG and IgM WB should always be used when the Lyme IgG/IgM antibody serology has returned an equivocal or positive result.

If the patient is highly symptomatic of Lyme, there is actually no point in doing the ELISA or EIA serum tests, as they do not have the sensitivity or specificity of the Western Blot that is needed to have a prayer of detecting Borrelia burgdorferi (Bb), the organism that causes Lyme disease.

In a sane world, wherein the CDC and AMA really did their jobs in protecting the public health and ensured the quick and proper diagnosis and treatment of patients infected with tick-borne infections, they would not bother with the ELISA and and similarly worthless tests and would, as you will read about below, pay attention to all the Bb specific WB bands when it came to Lyme testing. Alas, we live in this world, where, despite the publication of research from around the world, the CDC and AMA continue to ignore them, and recommend treatment protocols that result in undertreating active and latent or chronic infections, resulting in more people being sick and disabled by this disease.

Contrary to what many insurance companies believe, the IgG and IgM Western Blot for Lyme disease are not the same test. Some companies will deny one and pay the other, claiming they are the same test or duplicative of one another. IgG and IgM are two completely different antibodies.

IgM antibodies are the first antibodies to be produced in the body in response to an infection, and is produced in great quantity. IgM antibodies are large, up to six times larger than the IgG antibodies. IgM antibodies, when present in high numbers, represent a new active infection or an existing infection that has become reactivated. Over time, the number of IgM antibodies will decline as the active infection is resolved.

IgG antibodies are produced once an infection has been going on for a while, and may be present after the infection has been resolved. Generally speaking, the presence of IgG antibodies to an organism when accompanied by a negative IgM test for the same organism means that the person was exposed to that organism at one time and developed antibodies to it, but does not have a current active infection of that organism. When it comes to Borrelia burgdorferi (Bb), the organism responsible for Lyme disease, that is not necessarily the case.

To recap, depending on the numbers,

  • IgM is a sign of a current infection.
  • IgG is a sign of a current infection, or of a past exposure to or past infection by the organism.

Bb can hide in the brain and cerebral spinal fluid (CSF) and by altering its surface proteins, can remain invisible to the immune system for a long period of time. Once the immune system figures out what it is and starts making antibodies to it, it shifts is surface proteins once again, fooling the body into thinking the infection is over.

Bb can also turn itself into undetectable cysts and various other forms (called L-forms) which also help it elude the immune system. If the immune system can't see it, the immune system can't make and, or only insufficient antibodies, which all contribute towards making the organism impossible to detect by any testing methodology, including WB. Thus, blood and urine tests for Bb can be negative, even if the patient is "challenged" by being given high dose injections of antibiotics to try to trigger a reaction from or partial die-off of Bb that will cause it to show up in the blood or urine.

When a false negative is returned on a blood sample, it is called seronegative. There are many reasons why a seronegative result may be obtained. A seronegative result does not mean the person does not have an active or latent Lyme infection. It just means that this particular test was negative. That is why all the symptoms presented by the patient must be taken into consideration when making a clinical diagnosis, and why other appropriate testing should be done to rule out other causes for the wide range of symptoms being presented by the patient.

As can be seen from the table below, The CDC's criteria for what constitutes a positive result is very conservative. As a result, it is believed by those who have been treating Lyme patients for years, and by those developing other, more sensitive tests, that the CDC criteria miss most cases of borreliosis and, as a result of that underreporting, grossly understate the incidence of Lyme in the United States.

A Note On IGeneX
In late 2005, the New York Times knowingly published an inaccurate article about the accuracy of IGeneX's tests, including saying it had failed certification. In fact, IGeneX was in the midst of a routine recertification, something that all labs are required to do, and, as always, it passed, both in New York and California, the two most difficult states in which to get certified. If your doctor or family tells you IGeneX is 'bad', print out the the CLIA 2005-2007 certification and tell them to go do the research that the New York Times refused to do--and ignored when the certification was sent to them.

IgG considered positive if at least IGenex: 2 @ bands present
CDC: 5 # bands
IgM considered positive if at least IGenex: 2 @ bands present
CDC 2 #bands present

Note: The TBI tests done by MDL lay somewhere in between: not as sensitive as IGeneX (which uses two different strains of Borrelia), but not as extreme as the CDC's epidemiologic criteria for Lyme. IGeneX's FISH test for Babesia, and the antigen-in-urine test for Borrelia, are proprietary - no other lab does it.

The test kits MDL use are FDA-approved; the tests done by IGeneX are all proprietary. MDL will return more false negatives than will IGenex; both will produce more accurate positives than any lab looking at the restricted number of bands stipulated by the CDC's epidemiological criteria.





Band Definition

18 kDa


p18 flagellin fragment
22 kDa . . Immunogenic integral membrane lipoproteins. Cross-reactive with other spirochetes/bacteria. Depending on source, may be specific for Bb or cross-reactive. [Coleman]
23-25 kDa
@ #
@ #
OspC. 25 kDa is specific for Bb
28 kDa
OspD, Oms28. Specific for Bb
30 kDa
OspA substrate binding protein
31 kDa
34 kDa
OspB. Specific for Bb
37 kDa
p37, FlaA gene product. Specific for Bb
39 kDa
@ #
@ #
BmpA. Specific for Bb

41 kDa

@ #
@ #
45 kDa
[Flisiak]; appears for HGE [Ravyn]
58 kDa
66 kDa
p66 Oms66 Hsp outer/integral membrane protein
73 kDa
83 kDa
p83 high molecular mass protein. Specific for Bb
93 kDa
@ #
an immunodominant protoplasmic cylinder antigen, associated with the flagellum. Specific for Bb

Bb    Borrelia burgdorferi
Bmp  Bacterial membrane protein
Fla    Flagellin
HGE   Human granulocytic ehrlichiosis
kDa    kilodalton = molecular weight
Oms  Outer membrane-spanning
Osp   Outer surface proteins
p         Protein


Limitations and Notes
The bands in the above table apply primarily to the U.S. species/subspecies of B. burgdorferi. For band information on European and other species, please see Art Doherty's And The Bands Played On.

Positive (+ or +/-) IgG results on Bands 31 or 34 kDa may occur after vaccination in otherwise uninfected people.

IGeneX considers the IgM equivocal if only one of the @ bands are present.


Band Markings
When reporting bands, the reporting laboratory marks each band with the following indicators of intensity:

- Not present
+ Low
++ Medium
+++ High
+/- Equivocal = indeterminate (there, but not as intense as Low)



Art Doherty. And The Bands Played On

IGeneX, Inc. Lyme Disease Western Blot

Coleman JL, Benach JL. Characterization of antigenic determinants of Borrelia burgdorferi shared by other bacteria. J Infect Dis. 1992 Apr;165(4):658-66

Flisiak R, Wierzbicka I, Prokopowicz D. Western blot banding pattern in early Lyme borreliosis among patients from an endemic region of north-eastern Poland. Rocz Akad Med Bialymst. 1998;43:210-20.

Mervine, Phylllis. CALDA. Personal communication. 2004.

Ravyn MD, Goodman JL, Kodner CB, Westad DK, Coleman LA, Engstrom SM, Nelson CM, Johnson RC. Immunodiagnosis of human granulocytic ehrlichiosis by using culture-derived human isolates. J Clin Microbiol. 1998 Jun;36(6):1480-8.

Tylewska-Wierzbanowska S, Chmielewski T. Limitation of serological testing for Lyme borreliosis: evaluation of ELISA and western blot in comparison with PCR and culture methods. Wien Klin Wochenschr. 2002 Jul 31;114(13-14):601-5




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